Position indicator



Dec. 28, 1943. 5 WWW 2,337,613

POSITION INDICATOR Filed June '7. 1940 INVENTOR ATTORNEY Patented Dec. 28, 1943 UNITED STATES PATENT OFFICE POSITION INDICATOR Application June 7, 1940, Serial No. 339,301

4 Claims.

This invention relates to improvements in position indicating devices and has particular reference to an improved pitch angle indicator for a controllable-pitch propeller.

An object of the invention resides inthe provision of a relatively stationary indicator which will indicate the pitch angle of the blade of a rotating propeller and means between the indicator and the propeller for transferring pitch changing movements of the propeller blade to the indicator.

A further object resides in the provision of a light weight and relatively simple electrically actuated device for continuously indicating the pitch angles of the blades of a rotating propeller. A still further object resides in the provision of a pitch indicating device of the character indicated of high accuracy and sensitivity and which does not interfere with the construction or operation of the propeller.

Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawing, in which like reference numerals are used to designate similar parts throughout, there is illustrated a suitable mechanical arrangement of the invention. The drawing, however, is for the purpose of illustration only and is not to be taken as limiting or restricting the invention, as it will be apparent to those skilled in the art that various changes in the illustrated arrangement may be resorted to without in any way exceeding the scope of the invention.

In the drawing, the single figure is a longitudinal sectional view through a controllable-.

pitch aeronautical propeller showing the application thereto of a pitch indicating device constructed according to the invention.

. Referring to the drawing in detail, the numeral l generally indicates a propeller drive shaft projecting from an engine, not illustrated, and carrying the propeller and its pitch changing mechanism. The propeller may comprise two or more blades, one of which is indicated at l2, mounted upon respective radial bearing arms, as indicated at I4, provided on a propeller hub member or spider, generally indicated at I6. This propeller hub membermay be secured on the drive shaft by suitable means such as the cones l8 and 20, the threaded abutment portion 22 and the member generally indicated at 24 and the spline 26. The blades may be held in operative position on the hub member [6 by a suitable enclosure or barrel member, generally indicated at 28, and suitable anti-friction bearings may be interposed between this barrel member and the respective blades if desired. The member 24, secured to the ends of the shaft I0, is generally cylindrical and carries an outer cylindrical member, generally indicated at 30, which is operatively connected with the propeller blades through respective blade carried counterweights, one of which is indicated at 32, and is reciprocable relative to the shaft carried member 24. Both ends of the shaft carried member 24 are open but the outer end of the member 30 is closed by a suitable head member 34 and a fluid seal packing 36 is carried at the outer end of the member 24 and interposed between the members 24 and 30 to provide a fluid seal between-these two members. When hydraulic fluid is admitted to the interior of the hollow drive shaft Ill, in a manner well known to the art, it will flow through the drive shaft and through the member 24 and react against the head 34 to move the member 30 relatively to the member 24 thereby moving the counterweights 32 and turning the blade in a pitch changing direction.

For a more detailed description of a controllable-pitch propeller of the character indicated and a pitch controlling mechanism therefor, reference may be had to United States Patent No. 2,032,255 issued February 25, 1936, to Frank W. Caldwell for Propeller.

In carrying out the invention, one part of a two part electrical apparatus known to the trade as an Autosyn is rigidly secured in the member 24 by some suitable means such for example as being mounted in an aperture provided in the transverse partition 40 which partition is provided with additional apertures 42 for the free passage of hydraulic fluid therethrough. The other unit 44 of the electrical appartus is rigidly secured to some member such as the instrument panel 46 of an airplane.

Each of the units 38 and 44 comprises a relatively fixed stator and a wound rotor within the stator the winding being such that when the two rotors are electrically connected and the two stators are electrically connected and the two units are placed in circuit with a source of electromotive force, if the rotor of one unit is rotated the rotor of the alternative unit will rotate the same amount. In the illustrated arrangement the two stators and the two rotors are connected together by suitable electrical connections including the wires, one of which is indicated at 48, the ring and brush mechanism, generally indicated at 50, interposed between the rotating propeller and a fixed part of the engine, the wires one of which is indicated at 52, the insulated plugs, one of which is indicated at 54 leading from the exterior to the interior of the propeller, and the wires one of which is indicated at 56, leading from the respective insulated plugs 54 through the insulated plugs 58 and wires 60 to the terminal connection of the unit 38. While the wiring diagram between the two units 38 and 44 has been only schematically shown by means of a single conduit made up of various elements connected between the two units, it is thought that this illustration is sufiicient for purposes of the present disclosure as the manner of electrically interconnecting the two elements of an Autosyn is well known to the art.

The rotor of the unit 38 is connected to a screw shaft 62 which telescopes into a tube 64 secured at its outer end to the cylinder head 34 and which is provided with a threaded portion 536 cooperating with the threads of the member 62 so that the member 62 is rotated a predetermined amount whenever the member 48 moves relative to the member 34. As the movement of the member iii relative to the member 3 1 is directly proportional to the amount of pitch change of the propeller blade, the rotor of the electrical unit 3t will be moved an amount always equal to the pitch changing movement of the blades. Movements of the rotor of the unit 38 will caus a corresponding movement of the rotor of the unit M and this rotor is provided with a connection, such as the gears 68 and 10, with the pointer 72 of the pitch indicator, generally indicated at 5'5. Thus with the above described arrangement, the exact pitch of the propeller blade will be continuously indicated by the pointer 12 which pointer may cooperate with a suitable scale calibrated to indicate the pitch angle of the propeller blade referred to some datum pitch position.

While a suitable mechanical arrangement for disclosing the invention has been illustrated in the accompanying drawin and hereinabove described, it is to be understood that the invention is not limited to the particular arrangement so illustrated and described, but that such changes in the size, shape and arrangement of the various parts may be resorted to as come within the scope of the sub-joined claims.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

1. In combination, a rotatably mounted shaft having an axial passage therein, a variable pitch propeller fixed to said shaft including a reciprocable pitch changing element, a pair of electrical units having individual rotors, means supporting one of said units within said axial passage for rotation with said shaft, means for converting the reciprocatory movements of said pitch changing element into turning movements of the rotor thereof to turn said rotor in accordance with pitch changes of said propeller, means supporting the other of said units in a relatively fixed position, a pitch indicator operatively connected with the rotor of said other unit, and means including slip rings interconnecting said units in such a manner that when the rotor of said one unit is 70 turned the rotor of said other unit follows the movements of the rotor of said one unit and operates said pitch indicator.

2. A pitch indicator for a controllable-pitch propeller having a reciprocable pitch changing 6 element comprising, a pair of electrical units having individual rotors, means interconnecting said units in such a manner that when the rotor of one unit is turned the rotor of the other unit follows the movements of the rotor of said one unit,

10 means supporting said one unit in said propeller,

means comprising a screw shaft element and a cooperating nut element operatively associated with said propeller and the rotor of said one unit for converting the reciprocable movements of said 5 pitch changing element into turning movements of the rotor of said one unit to turn said rotor in accordance with the pitch changes of said propeller, and a pitch indicator operatively connected with the rotor of said other unit.

3. In combination, a rotatabl mounted shaft havin an axial chamber therein, a variable pitch propeller fixed to said shaft adjacent said chamber including a pitch changing membe reciprocable along said shaft and having an actuating 5 portion disposed axially in said chamber, a pair of electrical units having individual rotors, means supporting one unit within said chamber for rotation with said shaft with its rotor in axial alignment with said actuating portion, cooperating means on said actuating portion and the rotor said units in such manner that when the rotor of said one unit is turned the rotor of said other unit follows the movements of the rotor Of said one unit and operates said pitch indicator.

4. In combination, a rotatably mounted engine 5 shaft, a hollow axial extension on said shaft forming an axial chamber open at one end, a variable pitch propeller fixed to said shaft having a pitch changing mechanism including a sleeve reciprocable on said extension, a closure member for the free end of said sleeve also forming a closure for the open end of said chamber, an actuating member on said closure member extended axially into said chamber, a pair of electrical units, each having a rotor, means supporting one of said units in said chamber for rotation with said shaft with its rotor in alignment with said actuating member, cooperating means on said actuatin member and the rotor of said one unit for converting reciprocating movements of said sleeve into angular movements of the rotor of said unit in accordance with pitch changes of said propeller, means supporting said other unit in a relatively fixed position, a pitch indicator operatively connected with the rotor of said other unit, and means including slip rings for interconnecting said units in such manner that when the rotor of said one unit is turned the rotor of said other unit follows the movements thereof and operates said pitch indicator.

ERLE MARTIN. 

